A system on some machines, such as a track-type tractor machine, may maintain a constant speed of the machine by adjustment of an implement, such as a blade, and hence an adjustment of the load experienced by the implement. For example, adjusting an implement may include raising or lowering the implement. As more force is applied to the implement of the machine, ground engaging members of the machine such as tracks may slip, meaning the machine's track speed is not equal to its actual ground speed. For example, a drawbar holding the implement on some machines may experience increased force. Subsequently the tracks of the machine may slip. In such a case, the system may adjust the implement, such as by raising the blade, to reduce the load on the machine to maintain the desired speed and to reduce slip of the ground engaging members.
Often times, such as when the machine pushes a material, it is of interest to the operator to slow the machine. In this regard, the use of a deceleration control, such as a deceleration pedal, may limit engine speed, thereby reducing the speed of the machine. However, the above-noted system may determine that the machine is being slowed by the load on the implement and may raise the implement undesirably.
U.S. Patent Application Publication Number 2011/0040458A1, titled “Working vehicle engine output control system and method,” discloses an engine output control system which can compute a speed ratio of the torque converter and reduce an output torque of the engine without changing the target speed of the engine. However, this Application does not automatically adjust the target speed of the machine to maintain the load applied to the machine.
Accordingly, a system and method are needed to automatically adjust the target speed of the machine and maintain the load on the implement even when a deceleration control is applied.